When two spaces, e.g. two rooms of a building or the interior and the exterior of a building, shall be separated by a fire barrier wall, and a conveyor path extends through both spaces, it is usual to arrange a first conveyor leading up to an opening in said wall in one of the spaces and to have a second conveyor on the other side of such opening so that any article transported by the first conveyor can be transferred through the opening to the second conveyor. In this way, it is easy to arrange the plane of the shutter between both conveyors.
However, this approach has the disadvantage that many conveyor parts, particularly the driving arrangement, have to be doubled, because each of the conveyors has to be driven. Thus, although there is the advantage that no conveyor part which could interfere with the shutter when closing the opening in case of a fire, this approach is relatively expensive. Moreover, safe transfer of items is not ensured or has to be ensured by additional measures which will result in a further increase of costs.
German Patent No. 28 48 069 shows an approach for sealing a single continuous belt conveyor running horizontally through an opening in a fire barrier wall. In this case, the design relies on a material which foams under heat so as to seal all gaps. Within the range of the belt, foaming material is provided on the relatively broad front edge surface of the shutter as well as beneath the belt. In this way, a relatively large mass of foaming material has to be used not only to fill small gaps, but also relatively broad slots. Since such foaming material has a relatively poor heat conduction, there is the danger that it will predominantly foam at places where it is in contact with a material of higher heat conduction, while at other places foaming might not be ensured. Moreover, there is the danger that flames come directly in contact with this foaming material which is undesirable.
EP-Patent Nr. 0 124 910 relates to a fire barrier in a lift shaft of the paternoster-type. There are two guide rails extending through an opening of a horizontal wall, and articles are carried between them. However, such a design cannot be used without an appropriate modification for horizontal conveyors or conveyors with a horizontal component of movement where, in addition to a load carring section of an endless towing, such as a chain or a belt, there is also an idle section which has to be sealed.
Therefore, there is a need for improving the existing fire barriers in order to adapt them better to horizontal or substantially horizontal conveyors.